How to Make a Modded Minecraft Server from a CurseForge Modpack

Q: Can I run a Modrinth modpack the same way?

Yes. Modrinth packs (.mrpack) work the same way: same loader, same versions, upload the pack's overrides contents plus the mods. Many Modrinth packs also publish a server version.

Q: How do I update the modpack on my server?

Click Backup, check the new pack's loader version and set it if it changed, click Update game, then replace the mods and config folders with the new server pack's. Delete the old mods folder first so removed mods do not linger. Everyone then updates their client to the same version.

To make a server from a CurseForge modpack, download the pack's server pack from its Files page, run it on the same mod loader and loader version the pack uses (Forge, NeoForge or Fabric), give it at least 6 to 8 GB of RAM and the right Java version, then have every player install the exact same pack version through the CurseForge app. Most problems come from one of those not matching. Here is each step, plus the errors you will most likely hit.

Short answer

On the modpack's CurseForge page, open Files, pick the version your group will play and download its Server Pack from Additional Files.
Note the Minecraft version, the loader (Forge, NeoForge or Fabric) and the exact loader version.
Set up a server with that loader and version, on the right Java: 25 for 26.x, 21 for 1.20.5 to 1.21.x, 17 for 1.18 to 1.20.4.
Upload the pack's mods, config and other folders to the server.
Start it, wait for Done, and fix any errors in logs/latest.log.
Every player installs the same pack version in the CurseForge app and joins.

Step 1: Download the right server pack

A server pack is a cut down version of the modpack with client only mods (shaders, minimaps, menu tweaks) removed. Running the normal client pack on a server is the most common cause of startup crashes, so always start from the server pack if one exists.

Open the modpack on CurseForge.
Go to the Files tab and click the version you want. Use the newest stable version unless your group is already on an older one.
Under Additional Files, download the file marked as the server pack. Some packs also show a Download Server Pack option in the file's menu.

Write down the version number of the pack file. Players must install exactly this version, not "latest".

If a pack has no server pack, you can build one from the client files: install the pack in the CurseForge app, open its folder and copy mods, config, defaultconfigs, kubejs and any other non-client folders. Then remove the client only mods by hand. That last part is trial and error, which is why packs with an official server pack are much easier.

Step 2: Find the loader and Minecraft version

You need three facts:

Fact	Where to find it
Minecraft version	The pack's file page, for example 1.21.1 or 1.20.1
Loader	Same page: Forge, NeoForge or Fabric
Exact loader version	The server pack's installer file name (like `neoforge-21.1.x-installer.jar`), its `variables.txt` or readme, or `manifest.json` in the client pack

The exact loader version matters more than people expect. Mods in a pack are often tested against one loader build, and a newer or older one can crash on startup.

Step 3: Get the Java version right

Each Minecraft version needs a minimum Java version:

Minecraft version	Java
26.1 and newer	Java 25
1.20.5 to 1.21.x	Java 21
1.18 to 1.20.4	Java 17
1.17	Java 16
1.16.5 and older	Java 8

Older modded versions are pickier than vanilla. Forge packs for 1.16.5 and older were built for Java 8 and often break on anything newer, and some 1.20.1 packs are only tested on Java 17. If the server crashes before loading any mods with a Java error, this is usually why. Our startup crash guide shows what that error looks like.

New GamezServers Minecraft servers run on Java 25, which suits recent versions. If your pack needs an older Java, email support@gamezservers.com with the pack name and Minecraft version and we will move your server to the Java it needs.

Step 4: Give it enough RAM

Modpacks are where RAM matters. Use the pack page's recommendation if it has one, otherwise:

Pack size	RAM
Light pack, under about 100 mods, up to 10 players	6 GB, so the 8 GB plan
Big kitchen sink pack like All the Mods, up to 15 players	8 GB
Heavy pack with a bigger group	12 GB

On a modded server, RAM is used before anyone joins: every mod loads its blocks, items and recipes at startup. Too little shows up as a crash during loading or OutOfMemoryError in the log. Our Minecraft RAM guide goes deeper.

Step 5: Set up the server and upload the pack

On GamezServers

In Settings, under Server type, pick the pack's loader: Forge, NeoForge or Fabric, and click Switch. Your world is backed up first.
Set Minecraft version to the pack's version, for example 1.21.1.
For Forge or NeoForge, put the exact loader version from Step 2 in Exact Forge version or Exact NeoForge version. Leave it empty only if the pack does not care.
Click Update game to install that loader.
Stop the server. In Settings, click Show SFTP login and connect with FileZilla or WinSCP. Modpacks are hundreds of files, so SFTP is much faster than the browser.
From the unzipped server pack, upload these folders into the server's root, replacing what is there: mods, config, plus defaultconfigs, kubejs, scripts, resourcepacks or global_packs if the pack has them.
Skip the pack's own start scripts, installer jars, libraries folder and Java downloads. The server type already handles that.
Start the server and watch the Console.

The first start of a big pack takes a few minutes. It is done when the console says Done (...)! For help, type "help".

Self hosting

Unzip the server pack in an empty folder. Most packs include a start script (run.bat and run.sh, startserver.bat and startserver.sh, or similar) and a readme. The scripts usually install the loader on the first run. Set the RAM in user_jvm_args.txt (Forge and NeoForge) or the variables file the pack provides, accept the EULA in eula.txt, and run the script. Then forward TCP port 25565 on your router so friends outside your house can join.

Step 6: Get every player on the same pack

Players join with the CurseForge app:

Install the same modpack.
In the profile's settings, pick the exact same pack version as the server.
Give the game enough memory in the CurseForge settings. Big packs want 6 to 8 GB on the client too.
Launch, click Multiplayer, add the server address with the port, and join.

When you update the pack later, update the server and every player together. A single mod version difference is enough to block joining.

Common errors and fixes

Error	Cause	Fix
`Attempted to load class net/minecraft/client/... for invalid dist DEDICATED_SERVER`	A client only mod is on the server	The crash names the mod. Remove it from the server's `mods` folder.
`UnsupportedClassVersionError ... class file version 65.0` (or 69.0)	Java too old: 65 means Java 21 needed, 69 means Java 25	Use the Java from the table in Step 3
Crash during loading with no clear mod error on Java 25, old pack	Java too new for an old pack	Use Java 17 or 8 as the pack needs
`Missing or unsupported mandatory dependencies`	A mod needs another mod or a different loader version	Install the named mod, or set the exact loader version
`OutOfMemoryError: Java heap space`	Not enough RAM	Upgrade the plan, or remove heavy optional mods
Players are refused with a list of mismatched or missing mods	Client and server differ	Same pack version everywhere. Check you did not leave extra mods on the server.
Player times out while joining	Big pack sending lots of data at login	Try again once, check the client has enough RAM, then look at the server log for errors at that moment
Server stops with a watchdog error after startup	One tick took too long, often world generation	Pregenerate the world with Chunky, or raise `max-tick-time` in `server.properties`

When a crash report appears, open the newest file in the crash-reports folder and read the part under "Description" and the first lines of the stack trace. The mod at fault is usually named there. Mod loaders also print a list of loaded mods at the bottom, which helps spot the stray one.

Moving a singleplayer modded world to the server

You can bring the world you started in singleplayer: upload the world folder from the CurseForge instance's saves folder, then set level-name in server.properties to its folder name. The server and the world must run the same pack version. How to upload a world to a Minecraft server has the full steps.

FAQ

Do I need the CurseForge app on the server?

No. The server only needs the loader and the files from the server pack. Players use the CurseForge app (or another launcher that supports CurseForge packs) on their own computers.

Can I add my own mods to a modpack server?

Yes, but server side mods only go on the server, and anything that adds blocks or items must go on every player's client too. Back up first and add one mod at a time, so you know which one broke it if something does.

Can I run a Modrinth modpack the same way?

Yes. Modrinth packs (.mrpack) work the same way: same loader, same versions, upload the pack's overrides contents plus the mods. Many Modrinth packs also publish a server version.

Which modpacks are good for a server with friends?

Pick one built for multiplayer, with a server pack and active updates. Our list of the best Minecraft modpacks has options for tech, magic, exploration and light packs.

How do I update the modpack on my server?

Click Backup, check the new pack's loader version and set it if it changed, click Update game, then replace the mods and config folders with the new server pack's. Delete the old mods folder first so removed mods do not linger. Everyone then updates their client to the same version.

Run your modpack without the setup

On a GamezServers Minecraft server you pick Forge, NeoForge or Fabric in the panel, set the version, and the loader is installed for you. Upload the pack over SFTP, and keep 3 one click backups for updates. The 8 GB plan suits most big packs, and you can upgrade later without losing anything. For more on mods in general, read how to install mods on a Minecraft server.